Tarzan and the Sunken City of Atlantis

Upon saving Zupisa the great whale who had been beached, Tarzan discovers that Lord Cinnabar of Atlantis had enslaved the whales and uses them to power it while King Neptune is away. After leading a successful rebellion against the whales' slavery, Tarzan learns that Atlantis will flood unless power is restored and seeks help from Princess Aquila to find another way to power Atlantis.